Relay valve for tractor trailer brake systems



Oct. 20, 1953 c. B. FITES RELAY VALVE FOR TRACTOR TRAILER BRAKE SYSTEMS 2 Sheets-Sheet 1 Filed Nov. 5. 1949 an mw Rh mm mm QM 3 INVENTORI M f MfM, HIS ATTORNEYS.

Oct. 20, 1953 c FlTEs 2,656,014

RELAY VALVE FOR TRACTOR TRAILER BRAKE SYSTEMS Filed Nov. 3. 1949 2 Sheets-Sheet 2 FIG. 2.

INVENTORI B. 5111,

17%;mfM.

HIS ATTORNEYS- Patented Oct. 20, 1953 RELAY VALVE FOR TRACTOR TRAILER BRAKE SYSTEMS Cyril B. Fites, St. Johns, Mm, assignor t Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application November 3, 1949, Serial No. 125,331

4 Claims.

This invention relates to relay valves of the kind used in fluid pressure brake systems for automotive vehicles for applying fluid pressure to a fluid operated brake cylinder located at a distance from a main source of fluid pressure, such as in the case of brakes on a trailer of a tractor-trailer combination or on the rear brakes of a truck with a long wheel base, so as to cause the remotely located brakes to operate in response to an operators action as quickly as the front wheel brakes of the vehicle.

This invention also relates to emergency relay valves of the kindused in fluid brake systems for automotive vehicles for automatically applying the remotely located brakes when the pressure in the main reservoir of the system falls below a predetermined value for any reason.

This invention relating to relay valves and emergency relay valves is used in combination with a fluid pressure braking system having a main reservoir, an auxiliary reservoir, brake operating cylinders, a brake application valve, and comprises a housing having a diaphragm or diaphragms therein.

The object of this invention is to provide in a braking system, a relay valve having fewer parts, a more simple construction, and a more practical embodiment in that it provides a more rapid and positive action than those valves heretofore used.

Another object of this invention is to meter the amount of pressure fluid applied to the remotely located brakes to the exact amount de sired by the operator so that an operator can feel the application of said remotely located brakes and control said application in proportion to the application of his manual control means.

Another object of this invention is to provide in a braking system, an emergency valve having a simple construction of few parts which imparts a positive emergency action to an improved relay valve.

The invention also consists in the parts and arrangements and in the combination of parts hereinafter described and claimed. a

In the accompanying drawings, which form part of this specification and wherein like numerals refer to like parts wherever they occur:

Fig. 1 is a diagrammatic View of a fluid pressure brake system showing a longitudinal crosssectional view of the relay valve therein, and

Fig. 2 is a diagrammatic view of a fluid pressure brake system showing a longitudinal cross* sectional view of the emergency relay valve therein.

In Fig. 1 of the accompanying drawing, my relay valve l is shown embodied in a system having a main reservoir 2 supplied with fluid under pressure from a source not shown and connected with said relay valve l by a main reservoir line 3, an auxiliary reservoir 4 adapted for receiving pressure fluid from said main reservoir 2 and connected with the relay valve l by an auxiliary reservoir line 5, said relay valve I and auxiliary reservoir 4 being located near brake operating cylinders 5 which receive pressure fluid from said auxiliary reservoir 4 through a brake operating cylinder line i, and a brake application valve 6 connected with said main reservoir 2 by a line to, said relay valve I connected to said brake application valve 8 by a brake application valve line 9. Front brake operating cylinders 6a are connected to the brake application valve 8 by means of a brake operating cylinder line 1a. The brake operating cylinders 6 are remotely located and may be on the trailer of a tractortrailer combination or on the rear brakes of a truck having a long wheel base. The front brake operating cylinders 6a may be located on the front and/or rear brakes of a tractor in a tractortrailer combination or on the front brakes of a truck having a long wheel base.

The relay valve l comprises a left housing member ill and a right housing member I l rigidly secured together to form housing I 2 for the relay valve l. Secured in said housing l2 by its outer edge portion is a diaphragm l3 having a central opening therein for receiving an exhaust valve stem l4 rigidly mounted thereto by means of a lock nut l5 and a washer l6 cooperating with an exhaust valve stem flange I! on said exhaust valve stem M. Fitting circumferentially over the exhaust valve stem I4 is a packing cup 58 positioned between a shoulder l9 in the left housing member ii! and a packing cup retainer so which fits circumferentially over said exhaust valve stem M and in abutting relation to said lock nut 5. The exhaust valve stem I4 is provided with an exhaust valve stem passage 62 to connect a chamber 64 (to be described later) with an exhaust port 46; thus a means of exhausting pressure fluid from the brake operating cylinders ii is provided. A cavity is provided in the left housing member Ill which in conjunction with a diaphragm l3 forms an application chamber 53. The application chamber 63 is connected to the brake application valve 8 by the brake application valve line 9 and an inlet passage 2|.

The diaphragm l3 also forms a wall for another chamber 64, mentioned above, partially formed by a cavity in the left end of the right housing member H. A cupped guide member 22 having a cupped guide member flange 23 thereon is rigidly secured to the wall of the chamber 64 in axial relation to said exhaust valve stem [4 and surrounds said exhaust valve stem 14 allowing a passageway 24 therebetween. A diaphragm return spr n jrfi is positioned overrsaid cupped guide member-22 so as to rest uponthe cupped guide member flange 23 and abut against the exhaust valve stem flange l1. mediately to the right of the ,chamber.,54,is .,a valve chamber 65 having an outlet portfitifor connection with the brake operating cylinder line 1. An exhaust-actuatingvalve?26islocated within said valve chamber. -The -exhaust-actuating valve 26 comprises an exhaust-actuating valve stem 2'! having :an exhaust valve head 28 thereon with an exhaust valve head insert 29 therein, said exhaust valve head insert 29 being in axial alignment with the exhaust valve;stem l;4 tozcontrolsthe opening of the exhaust valve stem passageifi2 :jtherein, -and-'an ac tuating-"mlvespringidfl positioned raver said exhaust-actuating avalve stemqz'l between the exhaust valveihead 2-8 -and a' rib -section 3-! which isa partof the right housing 'member H. The exhaust-actuating valve stem 12! is extended to the right of the said rib section .3! into an actuatingichamber 136 :formed by .a closure cap '35 and :the right housing member .11. Secured to the right end of :-.the isaid exhaust-actuating valve stem 2"! isi-an actuating'valve head 32 with an actuating ivalve head insert "33 therein in abutting relation tOiRIl actuating valve seat 34 located .on said rib section 31 forcontrolling the opening formed bythe-said-rib section 3| between the valve chamber 65: and the -actuating chamber 36. An auxiliary reservoir port 3-1- is provided in the actuatingchamber 3,6 as .a means of connecting-the said actuating chamber as with the auxiliary reservoir line 5.

1n the lower portion of :the right -housing member 1 I is a check valve .38 for-allowing the flower pressure fluid tin only-one direction and comprising a slida-ble check valve-head 39 with a check valve in ert 40 in abutting relation to a check valve seat-4 inwsaid right housing memher I l, and a check valve sprina42 positioned between saidcheck valve head 39 and a check valve spring cap 4-3 whichformsa closure means for-the 'right housing member H. A'duct 44 leads from said check-valve 138'tothe actuating chamber 35. An inlet chamber 45 is located on the opnositeasideofi the'cheek valve 38 from the duct-44.

'In operation,- the'main reservoir z'is under fluid pressure from a source (not shown). When the pressure in" said main reservoir '2 exceeds a predetermined amount, the check valve 38 allows'fiuid to .pass therethrough into theduct 44 to the actuating chamber '36 and out through the auxiliary reservoir port3l and the auxiliary reservoir line into the auxiliary reservoir 4.

When the brake application valve 8 is actuated pressure fluid passes through the brake application valve line!) into the passage 2! and then into the application chamber 63 to force the diaphragm l3 rightwardly. Since the volume of the application chamber 63 is small, pressure canbe built up on the left side of the diaphragm l3 very quickly This pressure forces the diaphragm l3 rig-htwardly compressing the diaphragm return spring 25 and causing the exhaust valve stem l4lto -move rightwardly until itengages the exhaust valvehead insert 29 Located im-- creating an air seal therebetween thus closing the exhaust valve stem passage 62 in said valve stem I4 leading to exhaust port 45. Continued rightward movement of said diaphragm l3 and said exhaust valve stem !4 forces the exhaustactuating valve 25 rightwardly compressing the actuating avalve springruflrand oausingtithe actuating valvehead insert "33 to unseat. from the actuating valve seat 34, thereby allowing pres- ;sure fluid from the axuiliary reservoir 4 to come through the (auxiliary reservoir line 5, the auxiliaryreservoir port 31, the actuating chamber '36,'the valve chamber 65, the outlet port 66 and 'lputithroughzthelbrake operating cylinder line *7 into -the braleeioperating cylinders 6.

Whilepressure fluid is flowing through the .valve tchamberfieto the brake operating cylinders 6 a portion of the said pressure fluid also flows-through the clearance or passageway 24 between the exhaust valve stem I4 and the cuppedguide member 221-into the-ichamber t i. The passageway 2-4 is slightly restrictedso as to prevent a pressure 'build-upuin the chamber'64 ahead-0f that pressurewhich results from the flow of pressure fluidto-the brake operatingrcylinders ,6, whereby such *acondition if not ,prevented, would cause a fluttering -actionof the movable parts in the relay valve I. The movement of the exhaust valve within the passageway Hand the;pressure passing therethrough in both directions will aioliin keeping thepassageway clean of dirt and other extraneous material. .As the pressure fluid enters the chamber 64 a pressure is created :therein which in turn creates a force -on the 'diaphragm L3. The pressure in the. chamber 64 will therefore increase until the resultant force due to the presence of the pressure fluid-andtheforces- 0f the diaphragm return spring 25 and the-actuating valve spring 3!! overcome the force acting on the left side of :the diaphragm 1.3 in the application chamber 63. .As thiscondition occurs the diaphragm l3: and the attached exhaust valve stem 54 are moved to the left suflici'ently. tonallow the exhaust-actuating valve 26 to assume-a lapped position; that is, the actuating valve head insert 33 is :placed upon the actuating valve seat Hand the exhaust valve head insert 29 isstill held against the end ofth-e exhaust valve stem l4. Thus, the pressure in the chamber 6.4, which is equal to the pressure in the brake operating cylinders 6, will remain constant until. a further braking application is made by the operator by increasing the fluidpressurein the application chamber 63 :whereupon the diaphragm l3 isagain. moved to the: right. The exhaust valve stem l4, carried by said diaphragm i3 and by virtue of its contact with the exhaust valve head insert29, will again unseat the actuating valve head insert 33 from the actuating valve seat 34 permittinga flow'of pressure fluid from the auxiliary reservoir 4 as previously described. Consequently, it'becomes evident that a given pressurein'thetapplication fiuence of the greater pressure acting within the chamber 64 and the diaphragm return spring 25. The actuating valve head insert 33 having seated prior to the pressure reduction now being described, further movement of the exhaust-actuating valve 26 to the left is prohibited. When there is a complete reduction of the pressure formerly developed in the application chamber 63, the diaphragm I3 and the exhaust valve stem it move sufiiciently to the left to break contact between the end of the said exhaust valve stem i4 and the exhaust valve head insert 29 thereby opening the exhaust passage 62 in the said exhaust valve stem M. The pressure fluid in the chamber 64, the valve chamber 55, the brake operating cylinder line 1 and the brake operating cylinders 6 is then exhausted through the exhaust passage 62 and exhaust port 46 to the atmosphere.

In Fig. 2 of the accompanying drawing, my emergency relay valve 4'! is shown embodied in a system having a main reservoir 2 supplied with fluid under pressure from a source not shown and connected with said relay valve I by a main reservoir line 3, an auxiliary reservoir 4 adapted for receiving pressure fluid from said main reservoir 2 and connected with the relay valve i by an auxiliary reservoir line 5, said relay valve 2 and auxiliary reservoir l being located near brake operating cylinders E5 which receive pressure fluid from said auxiliary reservoir 4 through a brake operating cylinder line i, and a brake application valve 8 supplied with pressure fluid from the main reservoir 2 through the line is and connected with said relay valve by a brake application valve line 9. Front brake operating cylinders 6a are connected to the brake application valve 8 by means of a brake operating cylinder line la. The brake operating cylinders 5 are remotely located and may be on the trailer of a tractor-trailer combination or on the rear brakes of a truck having a long wheel base. The front brake operating cylinders 6a may be located on the front and/or rear brakes of a tractor in a tractor-trailer combination or on the front brakes of a truck having a long wheel base.

An emergency valve 48 is mounted on the relay valve hereinbefore described for forming the emergency relay valve M. The emergency valve 48 comprises an emergency valve housing 49 rigidly secured to the modified left housing member i e of the relay valve I for forming the emergency relay valve 41. Secured between the emergency valve housing 49 and the modified left housing member It is an emergency valve diaphragm 5t forming an emergency valve chamber 5! to the right of said emergency valve diaphragm 5%. A follower 52 is in abutting relationship to the emergency valve diaphragm 5t and fits within an emergency valve spring 53 which is held within the emergency valve housing 49 by an emergency valve spring retainer 5Q. Said follower 52 and the emergency valve diaphragm 5d are restricted from excessive leftward movement by virtue of the contact between the flanged portion of the follower 52 and the shoulder 55 on the emergency valve housing 49 when in the position shown in the drawing.

On the right side and in abutting relationship to the emergency valve diaphragm 523 is a relay valve operating stem base 56 and a relay valve operating stem 5'1. Fitting circumferentially over said relay valve operating stem 51 is a packing seal 58 held in position by packing seal retainer 59. A relay valve operating stem return spring 6!] fits over said relay valve operating stem 51 and abuts against the relay valve operating stem base 56.

An emergency valve passageway Bl connects the inlet chamber 45 in the relay valve l with the emergency valve chamber Si in the emergency valve 48.

In operation, the relay valve 1 portion of the emergency relay valve 41 operates as hereinbefore described. The pressure fluid in the main reservoir 2 is allowed to flow through the main reservoir line 3 to the inlet chamber 45, through the emergency valve passageway 61 into the emergency valve chamber 5| at all times where, if the resultant pressure is sufficient, it forces the emergency valve diaphragm 5Q leftwardly compressing the emergency valve spring 53 until the flange on the follower 52 abuts against the shoulder 55 on the emergency valve housing 49. This action allows the relay valve operating stem 51 to move leftwardly under the influence of the relay valve operating stem return spring 50 and away from the exhaust valve stem l4.

Therefore, so long as the pressure in the main reservoir 2 and its associated pipe system remain above a predetermined value, the relay valve l portion of the emergency relay valve 4''? operates exactly as hereinbefore described. But should there be, for any reason, a lowering of pressure below the minimum pressure required to sufficiently compress the emergency valve spring 53, the emergency valve diaphragm 59 will move rightwardly until the relay valve operating stem 5i contacts the exhaust valve stem it.

A further decrease in pressure will allow further rightward movement of said emergency valve diaphragm 56 thereby causing the relay valve operating stem 51 to move the exhaust valve stem t rightwardly just as if the operator had actuated the brake application valve 5%. The amount of movement of the emergency valve diaphragm 58 caused by any lowering of pressure is determined by the ratio of the area of the emergency valve diaphragm 5!] to area of the diaphragm 13.

An adjustment whereby a drop of 2 pound pressure below a predetermined value will cause a pressure of twice this amount to be applied to the brake operating cylinders works very satisfactorily.

In'the event of a complete breakaway of the trailer from the tractor the main reservoir line 3 is broken and the pressure in the emergency valve chamber 5! is immediately reduced to atmos pheric pressure thus allowing the emergency valve spring 53 to force the relay valve operating stem 51 rightwardly completely, thus forcing the exhaust valve stem Ml rightwardly closing the exhaust valve stem passage e2 therein and cansing the actuating valve head insert to unseat from the actuating valve seat 34, thereby allowing pressure fluid from the auxiliary reservoir s to come through the auxiliary reservoir line 5, the auxiliary reservoir port 31, the actuating chamber 36, the valve chamber 65, the port E2 6 and out through the brake operating cylinder line 1 into the brake operating cylinders 6. Having previously closed the exhaust valve stem passage 52 leading to the exhaust port AS, the position of all parts remains unchanged until pressure is again built up in the emergency valve chamber 5 I.

-What. l'clalm is 1... A; relay-valve.- comprisinga casing, arr-ex, haustport inthecasing, a single. diaphragm in the casing responsive for movement in-one direction to pressure froman application valve, a spring in the casing bearing against the non.- pressure side of the diaphragm and resisting movement of the diaphragm in one direction, a normally open exhaust valve comprising a hollow member, the exhaust valve being operatively connested to and extending through the diaphragm, one end of the exhaust valve being slidably mounted in the casing and extending into the exhaust port, the. spring cireumscribing ay portion Qf...athe exhaust valve, thexcasing. havinga guide passageway th.erein, a combinedfexhaustvalve seat and a normally closed actuating valvein the passages/.53, the other end of the exhaust valve extending into. the passageway engageable with 'theexhaust valve seat to close. the exhaust valve upon movement of the diaphragm upon the application of pressure to. the diaphragm, upon application of additional pressure to the diaphragm the exhaust valve moves the seat and thereby opens the normally closed actuating valve allowing the actuating pressure to pass theiethrough, the diameter or" the passageway being larger than the diameter of the actuating valve, the exhaust valve seat and the end of the exhaust valve extending. into the passageway thus forming a restricted lay-pass around that portion of theexhaust valve extending into. the passageway so that a portion of the actuating pressure passing around the actuating valve will hy-pass around that portion of the exhaust valve within the passageway and the exhaust valve seat to thenon-pressure side of the diaphragm to aid the spring in balancing excessive movement of thediaphragm andprovide smooth application of the actuating pressure.

. 2. In combination with. a fluid pressure brake system having a-main'reservoin-an auxiliary reservoir, means for allowing fluid pressure to flow from the main reservoir to the auxiliary reservoir, a brake application valve, and brake operating cylinders, a relay valve comprising a casing, an exhaust port in the casing, an application chamber. within the casing in connection with the brake application valve, 2. single diaphragmin the chamber movable inone direction in response to. fluid pressure from the application valve, a spring in the casing bearingagainst the non-pressure side of the diaphragm and resisting movement of the diaphragm in one direction, a normally open exhaust valve comprising a hollow member, the exhaust valve being pperatively connected to and extending through the diaphragm, one end of the exhaust valve being slidably mounted in the casing and extending into the exhaust port, the spring circumscribing b al eex n insi o the pa a way and-en a eahlewithcthe exhaust valve seat to. close the exhaust valve upon, the. movement of the diaphragmupon the application ofpressure to the diaphragm,..upon application of additional pressure to the;diaphragm the exhaust valvemoves the-seat and thereby opens the normally closed actuating valve allowing actuating pressure to now from theauxiliaryreservoir to the brake operating cylinders, the diameter of the passageway-being larger than the diameter of the actuating valve, thev exhaustvalveseat and the end of the exhaust valve within the passageway thus formin a restricted annular by-pass around thatpor-tion of theexhaust valve extending into the. passageway. so that a portion of the pressure passing around the actuating valve will by-pass around that. portion of the exhaust valve within the passageway and the exhaust valve seat to the non-pressure side ofthe diaphragm to aid. the spring in balancing excessive movement of the diaphragm and provide smoothapplioation of the actuating pressure.

3. A relay valve as set forth in claim 1 wherein the guide passageway is a bore within the casing closed at one end by a hollow cup member having a radial base flange, a forwardly extending circumferential vertical wall and a front wall having a centrally disposed opening therein, the end of the exhaust valve within the passagevay extending through the opening in the front wall, the diameter of the openings being larger than the diameter of that portion of the exhaust valve extending therethrough, and the spring having a portion thereof about the circumferential wall with an end bearing against the base flange and with. the other .end of the spring. hearing against the. exhaust valve.

i.v The combination asset forth in claim 2 in which the guide passageway is a bore within the casing closedat one end by ahollow cup member having a radial =base'flange, a forwardly extending. circumferential vertical wall and a front wall having a centrally disposed opening therein, the .end of the. exhaust valve within the passageway extending through the opening in the front wall, the diameter of the openings being larger than the diameter ofthat portion-0f the exhaust valve extending therethrough, and the spring having a portion thereof about the circumferential wall with an end bearing against the base flange and with the other end of the. spring bearingagainst the. exhaust. valve.

'CYRIL B. FITES.

Referenees Cited in thefile of this patent UNITED STATES PATENTS Number Name Date 765,638 'Schramm July 19, 1904 2,260,434 Campbell Sept. 28, 1941 2,289,559 Turek July 14, 1942 2,380,507 Eaton July 31, 1945 2 ,392,185 ;-Pickert Jan. 1; 1946 

